1. Field of the Invention
The present invention relates generally to techniques for coding and decoding of digital multimedia signals. More specifically, it relates to improved techniques for layered coding.
2. Description of the Related Art
(Note: This application references a number of different publications as indicated throughout the specification by one or more reference numbers within brackets, e.g., [x]. A list of these different publications ordered according to these reference numbers can be found below in the section entitled “References.” Each of these publications is incorporated by reference herein.)
A growing number of diverse data consumption devices (e.g., smartphones, tablets, smart-TVs, PCs) access shared sources of multimedia content over networks of time varying bandwidth and latency. In particular, the same content is delivered to various users at different data rates and quality levels. Obviously, different quality versions of a signal share a substantial amount of common information, whose exploitation is critical to ensure efficient use of resources for storage and transmission across the network. The simplest but highly wasteful approach is to store and transmit independent copies of the signal at different quality levels. A known alternative approach has each consecutive quality level subsume and refine the information transmitted in lower levels. This rigid hierarchical structure, popularly known as scalable coding, is widely recognized to incur significant quality loss, compared to individually encoded copies, and hence has not been adopted by most multimedia content providers.
To better understand the shortcomings of the prior art, some background information regarding prior art compression and networking technologies and, in particular scalable coding technology is provided.